1. Field of the Invention
The present invention relates to techniques for printing digital images and, more particularly, to techniques for increasing efficiency of printing in a digital image printing system.
2. Related Art
Digital photography is becoming increasingly popular and is generating a demand for increasingly easy, quick, and inexpensive ways to obtain prints of digital photographs. The options that currently are available to amateur users of digital cameras for obtaining prints, however, have certain limitations.
For example, a user who has digital photographs stored in a digital camera may print the photographs on a home printer, either by first transferring the photographs from the digital camera to a computer using a wired or wireless connection and then printing the photographs from the computer to the printer, or by inserting the digital camera's memory card directly into the printer and instructing the printer to print one or more of the photographs. In either case, printing on a home printer may be suboptimal for any of several reasons. First, the speed of home printers is typically limited, often requiring one or more minutes to print a single photo-quality 4″×6″ image. Printing a set of images from a vacation or other event may therefore require an hour or more. Furthermore, photo-quality images require a significant amount of ink to print. As a result, the user may be required to purchase many ink cartridges and to replace them frequently. Moreover, the user interface of the computer and/or printer may make it difficult to select and print the desired images, particularly if multiple copies are desired or if the user desires to print images on paper of varying sizes. Finally, the inkjet technologies that are used in most home printers produce images that are susceptible to fading after a relatively short period of time.
The home user may alternatively obtain prints from a commercial printing service. For example, the user may transfer digital photographs over the Internet to a service that prints the desired images, charges the user a fee, and sends the resulting prints to the user through the postal mail. Although prints obtained in this manner typically are of higher quality than can be obtained using a home printer, Internet photo-printing services can have certain drawbacks. For example, transferring large numbers of high-quality digital images to an Internet photo-printing service can take several hours over the 56K modem connection that is still used by most home users. Furthermore, transferring digital photographs to the computer so that they may be uploaded to the photo-printing service requires additional time and effort, as well as a degree of computer proficiency that home users may not have. In addition, the use of postal mail as the delivery mechanism means that the user must both pay an additional fee for postage and wait at least several days to receive prints.
An increasing number of walk-in photo development businesses are providing digital photo-printing services. To obtain prints using such a service, the user provides the service with the storage medium (e.g., memory card) from the user's digital camera and indicates which photographs are to be printed. The service prints the selected photographs and provides them to the user for a fee. Although such a service eliminates the problems associated with the use of postal mail delivery, problems remain. For example, the user may be required to wait a substantial period of time (such as an hour or a day) to receive the desired prints. As a result, the user may either need to wait at the store or make a return trip to pick up the prints. Furthermore, the service may not provide the user with the ability to preview photographs before they are printed, thereby making it difficult for the user to select the correct photographs to print. It may also be difficult or impossible for the user to select individual options for each photograph, such as the print size and image processing to be applied (e.g., red-eye reduction or contrast correction).
Digital photo-printing kiosks have been introduced in recent years in part as an attempt to address the problems described above. Such a kiosk is a self-contained device that includes a printer, a computer (including a display screen visible to the user), and one or more readers for reading digital images from storage media. A user may approach such a kiosk, insert a storage medium from a digital camera, use a graphical user interface to select one or more images to print, provide payment (such as by inserting a credit card), and then instruct the kiosk to print the selected images. The kiosk then prints the selected images and dispenses them to the user.
Such kiosks can be advantageous to the extent that they provide the user with a quick, easy, and flexible way in which to select, pay for, and obtain high-quality prints. Existing photo-printing kiosks, however, still tend to print at relatively slow speeds, often requiring thirty seconds or more to print a single photograph. As a result, a user who wishes to print a reasonable number of photographs may need to wait at the kiosk for a substantial period of time before all of the prints are complete.
Techniques that may be used to implement a high-speed photo-printing kiosk are disclosed in the above-referenced patent application entitled “A High-Speed Photo-Printing Apparatus.” Such a kiosk may, for example, include a print mechanism that has a throughput of 1-2 photo-quality images per second once the mechanism begins printing. Starting and stopping the print mechanism, however, takes time. If the print mechanism has finished printing one image and another image is not available to be printed, the print mechanism must be stopped and then restarted when the next image becomes available to print. Therefore, when using such a print mechanism to print a set of digital images, it is desirable to provide the images to the print mechanism in a manner which increases the likelihood that upon completion of printing an image, a subsequent image will be available to the print mechanism for printing. Providing images to the print mechanism in this manner would maximize the number of images that could be printed successively by the print mechanism and thereby minimize the time between the beginning and end of printing. In addition, it is desirable to begin printing as soon as possible after the user has issued a print command, so that the total printing time may be minimized.
For the foregoing reasons, there is a need for techniques for reducing the total time required to print digital images in a digital image printing system.